1. Field
Example embodiments relate to integrated circuit modules, for example, an integrated circuit module and method of forming the same.
2. Description of Related Art
Electronic instruments are becoming increasingly complicated in structure and more multi-functioned. As a result, the capacitance of integrated circuits including memory devices used in these electronic instruments may be increasing. Thus, the electrical instruments may tend to use a plurality of semiconductor memory devices as units of a memory module or integrated circuit module, rather than using individual semiconductor memory devices. The memory module or integrated circuit module may allow a plurality of semiconductor memory devices to be mounted on one printed circuit board (PCB).
FIG. 1 illustrates a conventional integrated circuit module.
Referring to FIG. 1, a conventional integrated circuit module 10 includes one or more semiconductor chips and a PCB 12.
The one or more semiconductor chips 14 may be structured in a ball grid array package (hereinafter, referred to as ‘BGA package’). The BGA package was developed in response to a requirement for more input/output pins and more efficient heat discharge due to an increased integration of semiconductor devices. A BGA package includes a plurality of external connection terminals, used as input/output pins, which are formed as an array on a face of the BGA package. A BGA package reduces the amount of mounting area required for the semiconductor chips and has a prominent heat resistance and electrical characteristic.
Though not shown in the drawing, a BGA package includes a semiconductor chip 14 having input/output pads and solder pads connected to the input/output pads. Solder balls may be attached to each of the solder pads.
A PCB 12 has a space for where at least one semiconductor chip 14 is mounted, and a circuit pattern is formed and connected to the at least one semiconductor chip. The PCB 12 also has a space for where a decoupling device is installed, and a circuit pattern is formed connected to the decoupling device. Further, the PCB has a space for where a circuit pattern interfaced with another PCB is formed.
In the PCB 12, solder pads to be connected to input/output pads of the semiconductor chip are installed at corresponding positions. The solder pads are electrically connected to the circuit patterns.
The semiconductor chip 14 is mounted on the PCB 12 by attaching the solder balls of the semiconductor chip 14 to the solder pads of the PCB 12. For example, the solder balls are heated above a melting point and attached to the solder pads of the PCB 12. The solder balls are formed of a conductive material, thus electrically connecting the semiconductor chip 14 and the PCB 12.
FIG. 2 is a plan view of a conventional PCB included in a conventional integrated circuit module. FIG. 2 schematically illustrates a mounted portion 20 of a PCB 12 where one semiconductor chip 14 may be mounted.
Referring to FIG. 2, solder pads 22 are disposed on the PCB 12 at positions corresponding to each of the solder balls or solder pads of the semiconductor chip 14. The solder pads 22 are coupled with circuit patterns 28, which may be coupled with other solder pads 22 in the mounted portion 20 of the PCB 12 or with via holes 24 that may be provided through the PCB 12. The via holes 24 may electrically connect the circuit patterns 28 with solder pads (not shown) formed on a face opposite to the mounted portion 20 of the PCB 12. For example, the via holes 24 may electrically connect symmetrical semiconductor chips mounted on opposite faces of the PCB. The circuit patterns 28 may be designed and disposed, corresponding to an operating characteristic of a mounted semiconductor chip 14.
A test pad 26 for a test or operation measurement is formed outside of the mounted portion 20 of the PCB 12. The test pad 26 is used to perform a test after mounting the semiconductor chip 14 on the PCB 12. A plurality of test pads 26 may be provided corresponding to the number of pads required for the test.
Problems in the wiring of the circuit patterns become more serious as a result of larger capacity and higher integration of an integrated circuit module. Even in an integrated circuit module in which wiring has been completed, a test signal line to evaluate a characteristic of the module, for example, to measure fidelity of the signals, may need to be added. However, solder pads 22 of an array type similar to that shown in FIG. 2 and/or input/output pads may be crowded, thus making it difficult to add a signal line or circuit pattern.